Abstract Introduction Radiation pneumonitis (RP) is a dose-limiting inflammatory complication of thoracic radiotherapy, affecting approximately 5-20% of patients. It commonly arises within 1-6 months following treatment and presents with cough, dyspnea, and hypoxemia. Early recognition and corticosteroid therapy are critical to prevent irreversible progression to radiation fibrosis and long-term pulmonary impairment. Case A 52-year-old male with stage IV right upper lobe lung adenocarcinoma undergoing concurrent carboplatin-paclitaxel chemoradiation presented after 5 months of treatment with worsening shortness of breath, dry cough, and persistent fever up to 104 °F. He was an ex-smoker with a 30-pack-year history and prior right MCA stroke on Eliquis. On presentation, BP was 103/73 mmHg, HR 129 bpm, Temp 103 °F, and SpO2 86% on room air. Chest examination revealed bilateral fine crackles and bronchial breath sounds over the right upper lobe. Chest X-ray showed right upper lobe consolidation and bilateral ground-glass opacities; CTA chest revealed patchy opacifications and mildly worsened right hilar lymphadenopathy. Laboratory evaluation demonstrated mild leukocytosis and elevated procalcitonin. Extensive infectious workup, including Mycoplasma, Legionella, Streptococcus pneumoniae, Histoplasma, and Pneumocystis testing, was negative. Bronchoscopy with BAL was unremarkable, and all cultures, including AFB and fungal, were negative. Radiation pneumonitis was diagnosed, and prednisone 60 mg daily with TMP-SMX prophylaxis led to rapid clinical improvement. Discussion Radiation pneumonitis (RP) is a noninfectious inflammatory response to thoracic radiotherapy, typically developing 6 weeks to 6 months after treatment. It results from alveolar epithelial and endothelial injury, causing cytokine-mediated inflammation involving IL-1, IL-6, TNF-α, and TGF-β, which leads to vascular permeability and interstitial damage. The risk is elevated with higher radiation doses, large irradiated lung volumes, and concurrent chemotherapy, particularly with platinum or taxane-based regimens. Clinically, RP presents with dry cough, progressive dyspnea, low-grade fever, and hypoxemia. Imaging typically shows ground-glass opacities or patchy consolidations confined to the radiation field, distinguishing it from infection or tumor progression. Laboratory findings often include mild leukocytosis and slightly elevated procalcitonin, with negative infectious workups. Corticosteroids remain the cornerstone of management; prednisone 40-60 mg daily is initiated for 2-4 weeks, followed by a gradual taper over 6-12 weeks. Patients on prolonged therapy require Pneumocystis jirovecii prophylaxis. Early identification and treatment are essential to prevent progression to chronic radiation fibrosis, which is largely irreversible. This patient’s improvement with corticosteroids supports the diagnosis and underscores the need for vigilance in recognizing radiation pneumonitis among oncology patients receiving concurrent chemoradiation. This abstract is funded by: None
Haqqani et al. (Fri,) studied this question.